The aquifer over exploitation in the central and northern part of Mexico requires efficient strategies in the application, savings, and conservation of water (blue gold) for the sustainability of horticultural crops like apple. So, the objective of this study was to compare the commercial irrigation (CI) with partial rootzone drying (PRD) in relation to the yield and fruit quality at harvest, and water productivity (WP). Emphasis was placed on water productivity, water relationships, tree nutrition, and postharvest performance of fruit. The treatments were: CI as control and PRD. Water productivity was significantly improved by the use of PRD and resulted in a water savings of 2.9 megalitres of water per hectare. Yield, yield components, vegetative growth, fruit size, and fruit quality were not modified by the irrigation treatments. Pruning weight was the lowest in PRD trees. Tree water status, stomatal conductance, and transpiration were lower in PRD trees than in RC trees. Except for calcium and boron, the concentration of the remainder nutrients was similar between treatments. After 18-day in storage, fruit quality was the same between treatments, but fruit water loss tended to increase in PRD fruit. In conclusion, PRD is a water-saving irrigation strategy for the sustainable apple production, mainly for areas where water resource is limited.

Little is known about the physiological processes involved in gas exchange of guava (Psidium guajava L.) leaves. In this research, the rates of CO2 net assimilation (A), respiration, and transpiration (E), and the stomatal conductance (gs), were measured in two stages of leaf development (mature and immature leaves) and in two levels of soil moisture (irrigated and drought stressed plants), on 3.5 years old guava trees planted in Iguala, Guerrero, México. The photosynthetic parameters in response to the intercellular concentration of CO2 (Ci) and to the photosynthetic active radiation (PAR) were also determined. Measurements were done with two portable photosynthesis apparatus, one of them equipped with devises for regulating PAR and Ci, keeping constant other environmental variables. It was found that immature leaves showed a lower A but higher respiration rate than mature leaves, and that the induced drought stress diminished gs by 50 % and A by 55 %, while E was completely inhibited. The photosynthetic parameters of guava leaves corresponded to a C3 plant since in response to Ci, A became saturated at 540 μmol·mol-1 and the compensation point occurred at 69.2 μmol·mol-1. In response to PAR, leaves reached photosaturation at 700 μmol photon·m-2·s-1 and the compensation point at 70 mmol photon·m-2·s-1.

Pruning is an essential practice to maintain the productivity in mango orchards. However, this labor is an uncommon practice in Nayarit, Mexico. Until now, it is unknown the more suitable pruning intensity to control the tree size and to get the best yields. The objective of this study was to evaluate the effect of pruning intensity on vigor, yield and weight fruit of ‘Ataulfo’ mangos. Three pruning intensities were evaluated, consisting of pruning at 50, 75 or 100 cm of all the shoots around the tree canopy. A control without pruning was also included. A completely randomized experimental design with 10 single tree replications was used. The main variables were vigor, yield and fruit weight. After the first year of evaluation, it was found that pruning facilitated to control the tree size since pruned trees had 10 % less height and 14 % less canopy diameter than unpruned trees. Pruned trees with 100 cm had the highest vegetative growth and the new shoot were longer with 31 cm; but the flowering in the immediately year after the pruning was the lowest with 16.50 %. Pruning intensity did not affected annual or accumulated yield of two years. In addition, it was noticed that any of the pruning intensities affected the fruit weight.

Mexico has been the leading import supplier of mango with an import market share of 56 percent for mangoes to USA. Since 2000, however, other countries, such as Brazil, Peru, Ecuador, and Belize, have also increased their share of the growing U.S. import market for this fruit. Michoacán is one of the more important Mexican producers. Due to the importance of this product, the research objective was to analyze the competitiveness of Mexican mango in front of its main competitors and to analyze the profitability in the region. The Mexican competitiveness at international level was estimated with the Indices of Revealed Competitive Advantage. At regional level, the profitability was estimating in 214 farms. Mexico has competitiveness with a negative tendency in relationship to Brazil and India. Mangoes are profitable for the region; nevertheless, the utilities are low due to the high costs per tons and low productivity.

Pecan (Carya illinoensis) is currently one of the most profitable crops in northern Mexico. There are several reports about different nutrimental imbalances affecting the yield and productivity of this species at the region identified as Comarca Lagunera, which shares portions of the States of Coahuila and Durango. This study was developed to calculate the preliminary compositional nutrient diagnosis (CND) norms of this species and to identify nutrient interactions. The yield target for mature fruit of this crop was assessed through the CND approach, as well as the corresponding optimum ranges of macronutrients (N, P, K, Ca, and Mg) foliar content, which are called CND nutrient norms. These norms qualify the minimum yield of 1.39 t·ha-1 for this crop. The statistical principal component analyses, performed using estimated CND nutrient indexes, allowed us to identify the following nutrient interactions: positive N-R, and negative N-Ca, K-Mg, and P-Ca.

A Software was developed for the formulation of nutrient solutions based on the universal method proposed by Steiner. The system contains a calculation module that allows to configure the formula according to the anion:cation ratio, total ionic concentration and the required pH. The interface includes automatic adjustment of the contributions of the chemical composition of the water for crop irrigation, as well as the management of a database that allows different combinations of fertilizers. User can access to a configuration menu to choose nutrient sources increasing by this way the portability of the system and facilitating the computation of solutions. By taking into account the results, the system presents more flexibility when eliminating the problems associated to the manual calculations and the restrictions to those that at the moment are subject the algorithms and the traditional spreadsheet focused to this end.

The objective of this study was to evaluate the effect of three integral management treatments on orchards at high densities on vigor, vegetative growth, flowering, yield, season of harvest, and fruit size of ‘Ataulfo’ mango. In a mango ‘Ataulfo’ orchard was selected under irrigation with high plantation density, three different integrated management treatments were applied. Each treatment included pruning (light and moderate) irrigation (application or suspension), fertilization (at specific phenological stage), foliar applications of nitrates or urea (to promote vegetative growth and flowering) and Paclobutrazol applied to the soil. The results showed that the three integral management packages showed benefits in diverse aspects: tree size was reduced; the flowering and yield was about for 30 days earlier than control trees; this performance allow us to get better prices when the harvest was obtained out of normal production time. The yield in the three treatments was higher than the control trees during 2007 and 2008. Cumulative yield of two harvests in the control trees was 75.65 kg·tree-1, while in the packages was among 149.40 and 163.59 kg. The average fruit weight was not affected by the treatment. The best package to be recommended is the number one, because it had the highest cumulative yield and it was the cheapest one.

Mining and metallurgy activities practiced in the Comarca Lagunera in Mexico have contaminated soil, air and water. The use of plants is one strategy for the remediation of soils contaminated with heavy metals. However, few studies on remediation with plants of arid and semiardid zones in association with mycorrhizae have been performed. The aim of this study was to evaluate the ability of pigweed (Amaranthus hybridus L.) to extract Pb and Cd by adding a mixture of arbuscular mycorrhizae (Entrophospora columbiana, Glomus intraradices, G. etunicatum, G. clarum) to the substrate contaminated with Pb or Cd. Two experiments, one for each metal, under the basis of an experimental design with randomized blocks with four replications were carried out. The first experiment considered three doses of mycorrhizae (0, 2.5 and 5.0 g·kg-1) added to the soil contaminated with 300 mg·kg-1 Pb. In the second experiment, we used the same quantities of mycorrhizae added to soil contaminated with 15 mg·kg-1 Cd. The concentration of Pb and Cd in root, leaf and stem at 65, 95 and 125 days of age of the plant were determined with an atomic absorption spectrophotometer. The results indicate that the addition of mycorrhizae significantly increased the concentration of Pb and Cd in root, stem and leaf. The concentrations of Pb and Cd were increased significantly as the age of the plant increases.

The present study was undertaken in order to asses the existing genetic diversity within a germplasm collection of avocado (Persea americana Mill.) kept at the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP) Campo Experimental Uruapan (CEFAP-Uruapan). The parental relationship among 77 accessions (231 plants) of the Mexican race was investigated by using seven Inter Simple Sequence Repeat microsatellites (ISSRs). A total of 154 loci were detected. Percentage polymorphism ranged from 82.3 to 95.4, with number of bands ranging from 17 to 25 within accessions. Genetic similarity analysis revealed formation of two major groups, one with eleven subgroups and the other one with three subgroups. Genetic similarity was highest between accession 237 (Atlixco, Puebla) and accession XTC01 (Uruapan, Michoacan), while accessions 532 (Atlixco, Puebla) and 369 (Chilchota, Michoacan) were the most dissimilar ones. None of the accessions were found to be duplicates. In general, the present study demonstrated the usefulness of ISSRs analysis for determination of genetic diversity in avocado.

The objective of the present work was to determine the effect of different doses of nitrogen (N) on the nutritional status of phosphorus (P) in roots and leaves of green bean plants (Phaseolus vulgaris L. cv. Strike), and also to examine the response of acidphosphatase activity as the main bioindicator of P. Nitrogen was applied to the nutrient solution as NH4NO3 and increasing doses of: N1 = 1.5 mM, N2 = 3.0 mM, N3 = 6.0 mM, N4 = 12.0 mM, N5 = 18.0 mM, and N6 = 24.0 mM of N were added. The results indicate that both deficient and toxic N doses were characterized by the lowest level of total, inorganic and organic phosphorus, as well as the highest activity of acid phosphatase; these effects are due to the direct influence between N and P levels. Treatment N4 presents the highest levels of the diverse fractions of P and the lowest activity of acid phosphatase. Additionally, it was found that the highest proportion of P in roots and leaves are in the forms of P-inorganic (Pi) and P-organic. These represented more than 65 % of total P, so it can be said that they represent the main forms of phosphorus in green bean plants. Finally, it should be noted that acid phosphatase activity was significantly correlated with Pi, which indicates that it can be used as a good indicator of the nutritional status of P in the roots and leaves of green bean plants.

In Nayarit, one of the most important problems in ‘Ataulfo’ mango is the presence of parthenocarpic fruits, which are smaller than normal ones. The objective was to know the effect of growth regulators on set and size of parthenocarpic fruit in ‘Ataulfo’ mango. This study was done during 2007 and 2008 in two commercials orchards whit high incidence of partenocarpic fruit (80 %). In both years, the following treatments were evaluated: gibberellic acid (GA3) 50 mg·liter-1; Agromil Plus® 2 ml·liter-1; Agromil Plus® 2 ml·liter-1 + GA3 50 mg·liter-1; GA3 50 mg·liter-1 + Thidiazuron (TDZ) 5 mg· liter-1 and a control. In 2008, GA3 (100 mg·liter-1) treatment was added, and the experiment was done in two locations. A completely randomized design with 10 replications was used in 2007 and a completely randomized design with factorial arrangement in 2008. In the Orchard 1, growth regulators increased fruit set (fivefold than the control trees); also, the fruit length was increased up to 59 % while the fruit weight was increased with all growth regulators twofold than the control trees. In the Orchard 2, the fruit length was increased up to 51 % while fruit weight wastwofold than the control trees. In the Orchard 2, the fruit set and the fruit size were greater than the orchard 1.

In México, the ‘Poblano’ pepper (Capsicum annuum L) has economic and cultural importance both fresh and dried. To produce dried red pepper also known as ‘Ancho’, is a problem because they require 10 to 15 days after harvest to develop the red color. In this work, we studied the effect of exogenous ethylene in ‘Poblano’ pepper on physiology and degreening ‘Poblano’ pepper postharvest. The fruits were harvested in two stage maturity (100 % green color and green with red areas d” 50 %), fruits were washed and treated with exogenous ethylene at 100, 500 and 1,000 μl·liters-1 in sealed chambers for 24 h at 25 ± 1 °C, 85-90 % RH, two lots of fruits were not treated with exogenous ethylene (Controls). The variables evaluated were: respiration rate and ethylene production, total soluble solids, titratable acidity, pH, moisture and external color. Exogenous ethylene increased the respiration rate and ethylene production of green pepper, but it not degreened. The best treatment was the application of 1,000 μl·liter-1 of exogenous ethylene in fruits harvested green with red areas (≤ 50 %), which were 100% red fruit at two days after of application ethylene. In the green fruits when applied, 500 μl·liter-1 of ethylene, for nine days of storage, were 20 % red fruits. Physicochemical changes were not affected by ethylene during storage.

The objective of this study was to evaluate the effect of 1-Methylcyclopropene (1-MCP) and ethylene (alone or combined) to handle the ripening process and to extend the shelf-life of ‘Maradol’ papaya. During 2007 three assays were conducted: 1. Effect of 1-MCP in papaya stored under marketing simulation and refrigeration plus marketing simulatio; 2. Papaya treated with 1-MCP and ethylene and the mixture of 1-MCP plus ethylene; 3. Commercial evaluation of 1-MCP and ethylene on papaya. Weight loss, external color, firmness, pulp color and total soluble solids were evaluated. It was found that 1-MCP at 100 nl·liter-1 delayed the development of external and pulp color, and inhibited the fruit softening. Also it was observed that ethylene at 100 μl·liter-1 applied after 1-MCP was unable to reverse the 1-MCP effect. However, 1-MCP applied after ethylene delayed fruit softening and the development of skin and pulp color induced by the ethylene application. It was concluded that 1-MCP at 100 nl·liter-1 for 12 hours applied after ethylene may be a viable technique to manipulate the ripening process and to extend the shelf-life of ‘Maradol’ papaya.

During 2007, a study was carried on pecan trees 8-years age applying Zinc. Orchard soil conditions were to a xerosol calcic, loam texture, alkaline pH and organic matter and CaCO3 contents of 1.09 and 12.84 % respectively. The experiment consisted on different applications of Zn products supplied from sprung leaf to maturity: Treatments were as followed: T1) Control, T2) NZN 100 mg·kg-1 Zn, T3) EDTA-Zn 150 mg·kg-1 Zn, T4) EDTA-Zn 100 mg·kg-1 Zn, T5) EDTA-Zn 50 mg·kg-1 Zn, T6) DTPA-Zn 100 mg·kg-1 Zn. Although none of the treatments significantly improved the concentration of zinc in the leaves, Zn-DTPA was a 34.84 % better than the other treatments. The values of chlorophyll in this study were 39,445 SPAD units, which is equivalent to 43 mg·litro-1 extractable chlorophyll, consistent with values of Zn deficiency, 20 mg·kg-1. The same applies to the leaf area index which is reduced by 30 % in conditions of deficiency. Results are preliminary due to that pecan trees present alternancy.

As the use of chemical fungicides to control postharvest diseases of apple as Penicillium expansum Link is not entirely accepted, antagonist microorganisms as yeasts are employed. However, due to their limited effectiveness they are proposed to be combined with substances of natural origin. To evaluate the efficacy of different strains of antagonistic yeasts in combination with sodium bicarbonate (SBC) to control P. expansum, ‘Golden Delicious’ and ‘Red Delicious’ apples were treated with three levels of SBC and inoculated with a given concentration of ten antagonistic yeasts separately in wounds where a spore suspension of P. expansum (1 x 104 UFC), was then placed. Lesion diameter and incidence were measured after ten days of incubation. ‘Red Delicious’ was less susceptible to P. expansum than ‘Golden Delicious’ (diameter lesion of 1.52 cm vs 2.01 cm). Yeasts with the highest antagonist capacity on P. expansum were 22-218, 8-121 y 26-224 (Torulaspora spp) reducing the development of fungus in 89, 81.8 y 84.3 % respectively. SBC did not reduce the development of fungus, but at 2 % it enhanced the antagonistic effect of yeasts 23-61 and 3-5241 in 26.4 y 23.1 % respectively. Yeast 22-218 showed the major antagonism against P. expansum in ‘Golden Delicious’ diminishing the lesion diameter at 0.1 cm, while yeasts 22-224 and 8-121 did in ‘Red Delicious’ diminishing injury in 91.7 and 91% respectively.

It is a need to know optimum concentrations and/or optimum ranges of nutrients useful for correct diagnosis and improvements of nutrient status of cultivated plants. Recognizing the need to develop correct nutritional standards, it is convenient to improve or to ensure the reliability of those already determined. Having in mind that aim, boundary-line approach standards were developed taking into account data acquired from a field experiment to study the effects of three fertilization treatments on yield of Opuntia ficus-indica L. The developed boundary-line approach standards were compared with already developed compositional nutrient diagnosis norms for N, P, K, Ca, and Mg concentrations in one-year old cladodes, and cladodes fresh matter as yield in order to define correct nutrient standards. The developed boundary-line approach optimum nutrient concentrations (associated to estimated maximum yield) for Opuntia ficus-indica L. are: N = 1.42 %, P = 0.38 %, K = 4.55 %, Ca = 2.83 % and Mg = 1.41 %. Results suggest that boundary-line approach estimated standards could be trustful and that lower and upper concentrations of the boundary-line approach sufficiency nutrient ranges could be also reliable as well as those for compositional nutrient diagnosis norms.